1. Field of the Invention
The present invention relates to an image observation apparatus for observing an image which a user observes by looking in through an ocular window (or eyepiece window) with the apparatus being held by a hand of the user or being fitted to a head of the user.
2. Description of the Related Arts
As this type of image observation apparatus, there has been conventionally proposed an image observation apparatus which has an image forming apparatus such as a camera or a computer graphic device, and an image observation apparatus body that is used in connection with the image forming apparatus. By constructing the image observation apparatus, in which the camera is used as the image forming apparatus, so that the camera is mounted on an image-taking direction controller which controls its image-taking direction of the image forming apparatus responsive to the posture (i.e. position and direction) of the image observation apparatus body, or by constructing the image observation apparatus, in which the computer graphic device is used as the image forming apparatus, so that its image data are processed or controlled responsive to the posture (i.e. position and direction) of the image observation apparatus body, the direction or orientation of the image can be changed in response to the movement of the user's head. With the system of image observation apparatus, the user can obtain a feeling as if the user himself or herself is present in the image while observing the image.
In order to realize the above function of the image observation apparatus, posture detecting means such as a position detecting sensor or an angular velocity detecting sensor, for detecting the position or direction of the user's head may be installed in the image observation apparatus body, and at the same time control means for controlling the image forming apparatus in response to the detecting signal transmitted from the posture detecting means may be installed on the side of the image observation apparatus body or on the image forming apparatus.
However, the present applicant finds out the following points. That is, the image observation apparatus body with the above mechanism generates or emits the detecting signal even when the user is going to observe a particular image with the image observation apparatus body in his or her hand, or even when the user is going to stop or terminate observing the particular image and to put the image observation apparatus body away from his or her eyes. Therefore, under these situations, the image is unnecessarily changed in response to the movement of the image observation apparatus body.
According to the above image observation apparatus, the image-taking direction is changed rapidly, so that there is a possibility that the durability of the image-taking direction controller may be impaired. Also, in case that a computer is used as the image forming apparatus, errors may be accumulated one after another as operation process is carried out many times. As a result thereof, there may arise a possibility of malfunction that the direction of image is not aligned with the direction of the user's head to which the image observation apparatus body is fitted, at time of resumption of observation.
Also, as this type of image observation apparatus, there has been conventionally proposed an image observation apparatus which has an image forming apparatus such as a camera or a computer graphic device, and an image observation apparatus body that is used in connection with the image forming apparatus, in which the image can be controlled by remotely operating the image forming apparatus from the side of the image observation apparatus body. For example, in case that a camera is used as the image forming apparatus, the camera is so constructed that the image-taking direction of the camera as well as the focal length and focal point of the photographing lens are adjustable so as to be able to control them remotely from the side of the image observation apparatus body. Alternatively, in case that a computer graphic device is used as the image forming apparatus, the computer graphic device is constructed so as to be able to control the operation process of image data from the side of the image observation apparatus body.
However, the present applicant finds out the following points. That is, according to the mechanism of the image observation apparatus, in case that the image condition remains the same as the image condition at time of the end of observation when the user restarts observation after the user stops the observation, and, for example, in case that the user tries to pursuit an object moving about on a wide area for monitoring the object by remotely controlling the image-taking direction of the camera as well as the focal length of the photographing lens, the user can not recognize the position and direction of the image if the image-taking direction (i.e. photographing direction) of the camera is not kept constant or stationary at time of resumption of observation. Also, under such a situation, if the focal length of the photographing lens is on the telephoto side, and if the angle of visibility is narrow, it would be difficult to correctly catch the image of the subject.
Such problems are caused by the fact that the image-taking direction of the camera as well as the focal length of the photographing lens are not kept constant at time of termination of observation so that the user can not immediately understand the condition of the image when the user resumes observation. Also, in case that a computer is used as the image forming apparatus, and in case that the image state is not kept constant at time of restarting observation, there would arise a similar problem that the user can not recognize the condition of the image at once.
Further, the present applicant also finds out the following points. That is, in case that the image observation apparatus body is equipped with an operational part for the user to remotely operate the image forming apparatus, any slight movement of the image observation apparatus body during operation of the operational part by the user is detected by posture detecting means. As a result, the image forming apparatus is unintentionally controlled against the intention of the user. That is, there is a possibility that the image under observation may swing, flutter or move along with movement of the user's hand during operation or handling of the image observation apparatus body.